Neurotoxic esterase (NTE) is believed to be the site of the primary biochemical lesion in organophosphorus-induced axonopathy. Work is underway to define the subcellular localization of NTX in hen brain and to isolate and purify the enzyme for more detailed mechanistic studies. Occurrence for inhibition by neurotoxic and non-neurotoxic organophosphorus compounds. A species comparison is also to be carried out, including species resistant to organophosphate neuropathy.